A New York man's alleged contract and e-mails that supposedly gave him 50 percent ownership in Facebook are forgeries, according to a court filing by Facebook CEO Mark Zuckerberg.

Zuckerberg said in a filing today in U.S. District Court in Buffalo, N.Y., that he declared under oath that he did not sign a contract with Paul Ceglia regarding Facebook or write the alleged e-mails regarding the social-networking giant's creation. (Text of the filing is available below.)

Facebook founder and CEO Mark Zuckerberg
James Martin/CNET

"Zuckerberg and Ceglia never discussed Facebook and they never signed a contract concerning Facebook," the filing said. "The contract is a cut-and-paste job, the e-mails are complete fabrications, and this entire lawsuit is a fraud."

Electronics forensics experts were unable to find alleged e-mails supporting Ceglia's claim in Zuckerberg's Harvard account, finding instead e-mails that "contradict Ceglia's made-up story," the filing said. Zuckerberg requests the original contract, e-mails in native form, and inspection of all computers in Ceglia's possession as well as those in his parents' house.

Zuckerberg acknowledged in today's filing that he signed a contract to write code for a Ceglia project called StreetFax but said the contract was "doctored" to make it appear to be about Facebook development.

"Among other things, the column widths and margins are inconsistent, which indicates that the document has been altered and reproduced," the claim said. "Many words and sentences simply make no sense, and the document is riddled with internal inconsistencies and contradictions strongly indicative of fraud."

Ceglia's legal representatives in the matter said they were eager to make the contract and e-mails available to Zuckerberg and Facebook.

"Mr. Ceglia welcomes the opportunity to expedite discovery in this case and disagrees with the opinions within the filing, which have been made by those who have not examined the actual contract at issue in this case or any of the other relevant evidence," reads a statement from Ceglia's law firm, DLA Piper.

Ceglia, of Wellsville, N.Y., claimed in a lawsuit filed last year that he entered into a contract with Zuckerberg in 2003 to design and develop the Web site that would ultimately become Facebook--a company that now has an estimated value of $50 billion.

Ceglia said he hired Zuckerberg through a Craigslist ad to write code for a project called StreetFax and paid Zuckerberg $1,000 for coding work; he also allegedly invested $1,000 in Zuckerberg's The Face Book project, which gave him a 50 percent interest in the company as well as an additional 1 percent interest for every day after January 1, 2004, that The Face Book was delayed.

In a revised complaint filed in April, Ceglia cited more than a dozen e-mails purportedly between himself and Zuckerberg that detail discussions on design, development, business plans, and eventual contract disputes regarding The Face Book.

Last year, Ceglia produced a canceled check that he said proved he paid Zuckerberg $3,000 for some freelance software development work for a project called "The Face Book." Facebook initially said it believed the contract was a "likely" forgery. It has since become more forceful and said it considers it to be an outright fake.